The location of cues promoting selective reinnervation of axolotl muscles

Abstract

The selective reinnervation of muscles suggests that muscles have intrinsic recognition cues that promote selective synaptogenesis. For example, the anterior and posterior heads of the axolotl iliotibialis (ILT) muscle are preferentially reinnervated by their original motoneurons even after surgically exchanging them. The nature and location of cues that promote such selectivity are unknown, although previous work suggests that the muscle fibers themselves might harbor the relevant molecules. To address this question, we removed anterior and posterior ILT muscles, destroyed their myofibers by surgically damaging them and treating them with bupivacaine, and reimplanted them in either a normal or a reversed anterior/posterior orientation. After the regenerated myofibers became innervated, we stimulated different spinal nerves and recorded the synaptic potentials evoked in muscle fibers. Our results showed that if the muscles were removed, damaged, and reimplanted in their original positions, the segmental origin of inputs to the regenerated myofibers was similar to that seen in normal muscles and in muscles reimplanted with their myofibers intact. However, muscles that were removed and damaged but regenerated in new positions were innervated differently from normal muscles and from muscles whose myofibers survived transplantation. Thus, the site at which a muscle regenerates has an influence on the source of the muscle's reinnervation. Nevertheless, the innervation of muscles that regenerated after transplantation to a foreign site was not strictly appropriate for the new position, but was biased towards the muscle's original innervation pattern. Therefore, some, but not all, of the cues that reflect the original identity of the transplanted muscles survive the replacement of its myofibers.

The Effects of Chronic Electrical Stimulation on Laryngeal Muscle Reinnervation

“…The specificity between a single neuron and its endplate is established during development with the competitive elimination of redundant innervation [17]. Following denervation in the adult, motoneurons revert to a more embryonic or dedifferentiated state, but retain some specificity for their original muscle target [18][19][20]. Denervation induces formation of extrajunctional (de novo) receptors on each muscle fiber [21].…”

Selective elimination of cross-compartmental innervation in rat lateral gastrocnemius muscle

“…Several experiments have demonstrated that selective reinnervation of muscles can occur (Wigston andSanes, 1982,1985;Laskowski and Sanes, 1987;Wigston and Kennedy, 1987). It has been suggested that muscles possess intrinsic recognition cues that promote selective reinnervation, even when muscles are transplanted to novel locations (Wigston, 1986) and that some of this selectivity can be abolished by destroying a muscle's fibers (Wigston and Sanes, 1985;Wigston and Donahue, 1988). It is possible that these postulated recognition cues are generally compartment-specific and that this specificity underlies the selective innervation of neuromuscular compartments that we have observed at birth.…”

Inaccurate projection of rat soleus motoneurons: A comparison of nerve repair techniques

“…Selective reinnervation has been reported to occur after transection of motor axons in neonatal rats, 2,14 larval anurans, 10 and adult urodeles. 29 Hardman and Brown 14 demonstrated that reinnervation of intercostal muscles of neonatal rats was topographically correct, whereas reinnervation in adult rats appeared to be random. Further, Gillespie et al 12 demonstrated nonselective innervation of rat lateral gastrocnemius and soleus muscles when the common nerve branch to these muscles was cut and sutured to the lateral gastrocnemius muscle.…”